Steel alloys containing hard metal compounds, exemplified by titanium carbide, are necessarily made by powdered metal metallurgical techniques. Such an alloy comprises the hard metal compound particles dispersed in a steel matrix. Although used for cold-working tools, and certain structural parts, they are particularly adapted for tools and other parts subjected to wear when working at high temperatures.
From the German Pat. Nos. 1 257 440 and 1 558 477, sintered steel alloys are known with 27 to 35% TiC and a matrix alloy of
______________________________________ less than 0.03% C 3 to 7% Mo 12 to 26% Ni 5 to 11% Co 0.15 to 2.4% Ti 0.05 to 0.6% Al 0.02% B, remainder, Fe, ______________________________________
where 50% of the Ni content can be replaced by Cr.
From the German Pat. Nos. 1 298 293 and 2 061 486, the following sintered steel alloys are known:
______________________________________ 20 to 80% by volume TIC and remainder, i.e., 20 to 80% by volume steel with 10 to 36% by weight Ni 0.2 to 9% Ti up to 5% Al, the sum Ti + Al not to exceed 9% up to 25% Co up to 10% Mo, remainder, Fe ______________________________________
or with
______________________________________ 12 to 20% by weight Cr % Cr/2 + Ni not to 4 to 10% Ni exceed 15% 3 to 10% Co up to 5% Mo 0.5 to 5% Ti up to 5% Al less than 0.02% C, Remainder at least 50% Fe. ______________________________________
These prior art sintered steels carry the hard metal compound in a matrix of steel containing sufficient nickel to make the steel more or less martensitic and which, therefore, can be called nickel-martensitic steel alloys. In addition, it is to be noted that their molybdenum contents do not exceed 10% by weight. It has heretofore been believed that a molybdenum content exceeding this value would result in the alloy being excessively brittle.